(a) Field of the Invention
The present invention relates to a ventricular assist device cannula and a ventricular assist device including the same.
(b) Description of the Related Art
A ventricular assist device (VAD) is generally used in the case where an internal treatment has no effect on patients with heart failure or the heart failure is difficult to treat by open heart surgery. The ventricular assist device is operated so as to replace the function of a ventricle before imprinting a heart or used in order to induce recovery by reducing a load of the heart. The ventricular assist device generally has a structure which aspirates blood from an atrium or a ventricle by using a cannula and then ejects the blood to the aorta.
The ventricular assist device is classified into an implantable type ventricular assist device and an extracoporeal type ventricular assist device according to an implanted region and into a left ventricular assist device (LVAD), a right ventricular assist device (RVAD), and a biventricular assist device (BiVAD) according to an assisted heart region. The left ventricular assist device is mainly used. In addition, as another classifying method, the ventricular assist device may be classified into a pneumatic type and an electric type according to a difference in methods of supplying a power source. The electric type is sub-classified into an electrohydraulic type and an electromechanical type. In addition, the ventricular assist device may be classified into a pulsatile type and a nonpulsatile type according to the existence of pulsation when the blood is ejected according to a driving manner. In addition, an implantable biventricular assist device corresponds to a mechanical heart, but is differentiated from a totally implantable mechanical heart in which blood circulation is performed by only the mechanical heart after removing a natural heart.
Since a patient with a terminal heart disease using the ventricular assist device complexly shows problems such as the loss of a pumping function of the heart, arrhythmia or ventricular fibrillation, and ischemia, it is difficult to expect a significant improvement of the survival rate of the patient by using only the ventricular assist device.
For example, even though the patient with the terminal heart disease uses the ventricular assist device, the patient may die from interruption of pulsation of the heart. Therefore, the survival rate needs to be increased by using a defibrillator together. Further, it is almost impossible to anticipate the pulsation timing of the heart of a patient with arrhythmia, a possibility that simultaneous pulsation which may impose a burden on the heart may occur is very high. Therefore, an artificial pacemaker capable of adjusting the pulsation timing of the heart needs to be used in conjunction with the ventricular assist device.
However, since a separate electrode for applying an electric stimulus to the heart has to be transplanted in order to mount the defibrillator and the artificial pacemaker, respectively, an additional operation and an in-vivo volume of the patient are required.
Meanwhile, when a separate external defibrillator is used, malfunction and damage of the ventricular assist device may occur.
Meanwhile, the existing ventricular assist device can measure or estimate its own blood ejection amount, but since the existing ventricular assist device cannot find a cardiac ejection amount of a patient and a total blood circulation amount, the existing ventricular assist device cannot perform optimal control according to a physiological condition of the patient. When the ventricular assist device is used, an optimal amount of blood flow which the ventricular assist device will supply depending on the physiological condition of the patient is changed. It was difficult for the existing ventricular assist device to be equipped with an appropriate measurement device for expecting physiological variation of the patient. If a blood flow supply amount of the ventricular assist device is excessively large, arteries or heart tissues around an inlet catheter may be narrowed or damaged and if the blood flow supply amount thereof is excessively small, an effect of assisting the heart is reduced. Further, when the ventricular assist device co-pulsates while the heart pulsates, a large load is applied to a heart muscle to damage the heart muscle. Therefore, a measurement technology which can be easily applied to the existing ventricular assist device simultaneously when measuring the cardiac output and a cardiac ejection timing of the patient needs to be developed.
Meanwhile, the artificial pacemaker which normally pulsates the heart by using an electric stimulus principle is primarily used for a patient who has a pulse slower than a normal pulse or is under a risk of an expected death. The artificial pacemaker is constituted by two parts of a pace generator and an electrode line. Between them, the pace generator is a metallic case including an electronic circuit controlling the electric stimulus and a battery and the electrode line serves to pulsate the heart by transferring electricity or send an electrical signal generated from the heart to the pace generator. The artificial pacemaker is divided into a temporary type and a permanent type. In the temporary type, the power supply is provided outside the body and is used for a patient who requires pacemaking for several days. The permanent type is used for a patient who requires pacemaking for a long period of time with a power supply thereof buried in the body. The pace generator is buried below a skin of an upper part of a chest and the electrode line is inserted into the blood vessel to be connected to the inside of the heart. The electrode line may be fixed to the heart muscle. The artificial pacemaker has a light weight of 20 to 30 g and also has a small size. The life-span of the battery is continued for 7 to 13 years. Further, there is also provided a fully automatic type which has an output of the power supply and pulsation rate which can be controlled outside the body and functions similar to a normal heart so as to allow the patient to act similarly to a normal person.
Actually, it is almost impossible to anticipate a timing of the heart beat of the heart of the patent with arrhythmia. Accordingly, when only the ventricular assist device is used, a possibility that simultaneous pulsation which may impose the large burden on the heart will occur is very high.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.